A common thing to need to do is to remove some text from a subject when importing from a mailing list. Another common thing to do is to remove a footer from a message from mailing list.

It would be nice to have a third mangling pass to do custom things in addition to these two.

So I guess the suggestion is to add a specific footer removal mangling option and leave the current body mangling as something specific. You could even pre-populate the footer mangling with the generic email signature setting and then let the user customise it if they want.

Finally, this should be consistent across the mailing list, nntp syncing, XML aggregator, and any other syncing channels that come into being.